1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and a method of manufacturing the same.
2. Description of Related Art
A typical LCD device includes lower and upper substrates with a liquid crystal layer interposed therebetween. The lower substrate has a thin film transistor (TFT) as a switching element and a pixel electrode, and the tipper substrate has a color filter and a common electrode. The pixel electrode serves to apply a voltage to the liquid crystal layer in conjunction with the common electrode, and the color filter serves to implement natural colors.
FIG. 1 is a plan view illustrating a lower array substrate of the conventional LCD device. As shown in FIG. 1, the lower array substrate includes gate lines 60 arranged in a transverse direction, data lines 70 arranged in a longitudinal direction, TFTs arranged near the cross point of the rate and data lines 60 and 70, and pixel electrodes 40 arranged on a region defined by the gate and data lines 60 and 70. Each of the TFTs includes a gate electrode 60a, a source electrode 70a, a drain electrode 70b, and a semiconductor layer 80. The gate electrode 60a extends from the gate line 60, and the source electrode 70a extends from the data line 70. The drain electrode 70b is laterally spaced from the source electrode 70a and is electrically connected with the pixel electrode 40 through a contact hole 90. A portion 35 of the pixel electrode 40 overlaps over the gate line 60, so that a storage capacitor is formed.
FIG. 2 is a cross sectional view taken along line IIxe2x80x94II of FIG. 1. As shown in FIG. 2, the gate electrode 60a is formed on the substrate 100. The gate electrode 60a is made of a metal such as Al, Mo and Cr. A gate insulating layer 30 is formed on the exposed surface of the substrate 100 while covering the gate electrode 60a. The semiconductor layer 80 is formed over the gate electrode 60a. The semiconductor layer 80 is made of an amorphous silicon. An ohmic contact layer 81 which is ion-doped by impurities is formed on the semiconductor layer, and a portion of the ohmic contact layer 81 over the gate electrode 60a is removed. The source and drain electrodes 70a and 70b overlay the ohmic contact layer 81 at both end portions of the semiconductor layer 80. A passivation film 50 is formed over the whole surface of the substrate while covering the source and drain electrodes 70a and 70b. The passivation film 50 has the contact hole 90 therein to expose a predetermined portion of the drain electrode 70b. The pixel electrode 40 is formed on the passivation film 50 and is electrically connected with the drain electrode 70b through the contact hole 90.
FIG. 3 is a cross sectional view taken along line IIIxe2x80x94III of FIG. 1. As shown in FIG. 3, the two adjacent pixel electrodes 40 are spaced apart from each other, and the passivation film 50 is interposed between the data line 70 and the pixel electrodes 40. Also, the pixel electrodes 40 are horizontally spaced apart from the data line 70. A black matrix (not shown) is arranged on the upper substrate to cover a space between the data line 70 and the pixel electrode 40, so that light leakage is prevented. Parasitic capacitors cd1 and cd2 are formed between the data line 70 and the two adjacent pixel electrodes 40. The capacitance of the parasitic capacitors cd1 and cd2 increases as a distance between the data line 70 and the pixel electrode 40 becomes smaller. Due to the parasitic capacitors, voltages applied to the data line 70 are distorted and cross talk occurs, leading to poor display quality. Decreasing the parasitic capacitance by lengthening the distance between the data line and the pixel electrode results in a lower aperture ratio.
For the foregoing reasons, there is a need for a liquid crystal display device that can decrease the effects of a parasitic capacitance formed between a data line and a pixel electrode and thereby improve an aperture ratio and a display quality.
To overcome the problems described above, preferred embodiments of the present invention provide a liquid crystal display device having a high aperture ratio and a high display quality.
For example, a preferred embodiment of the present invention provides a liquid crystal display device, including an upper substrate having a color filter and a black matrix; a lower substrate having: a gate insulating layer formed thereon, a data line formed on the gate insulating layer, a light shielding pattern formed on the gate insulating layer and spaced apart from the data line, a passivation film formed over the gate insulating layer, the data line, and the light shielding pattern, and a pixel electrode formed on the passivation film and overlapping a portion of the light shielding pattern; and a liquid crystal layer interposed between the upper and lower substrates.
As a further example, another embodiment of the present invention provides a method of manufacturing a liquid crystal display device, including forming a gate insulating layer on a substrate; depositing a metal layer on the gate insulating layer; patterning the metal layer to form a data line and a light shielding pattern spaced apart from the data line; forming a passivation film over the gate insulating layer, the data line, and the light shielding pattern; and forming a pixel electrode on the passivation film, the pixel electrode overlapping a portion of the light shielding pattern.
The present invention, among other things, advantageously lowers the parasitic capacitance between the data line and the pixel electrode, thereby bringing about a high display quality and a high aperture ratio.